1. Field of the Invention
The present invention relates to a heating device equipped with thin heating boards that include graphite layer electrically connected with a power control device so as to dispense even and warm heat energy.
2. The Prior Arts
FIG. 1 shows a conventional heater 10, which includes a case with a curved reflection board 13 and a quartz tube 11 is connected between two sidewalls of the case. The quartz tube 11 can be heated to very high temperature so that a plurality of separation grids are used to separate users and the quartz tube 11. The grids are arranged to have a certain width of gaps so as to let the heat to be reflected toward the users. However, the quartz tube 11 might burn flammable material such as paper sheets or even burn the users who unintentionally touch the quartz tube 11. Besides, only a short distance in front of the heater 10 feels the heat.
FIG. 2 shows another heater 20, which includes a plurality of blades 21 and oil is circulated between the blades 21. A heating device 22 is used to heat the oil and the oil circulates through the blades 21 to heat the blades 21 and then, to make heat exchange with the air. The oil is evenly heated and does not have very high temperature so that it will not burn the users. However, the efficiency of heat transferring is low. Most of the blades 21 are coated with a layer of baking vanish which reduces the heat transferring from the blades 21 to the air. Besides, the heater 20 is not an energy saving heater.
FIG. 3 shows yet another heater 30, which is used in a sauna cabinet and includes a plurality of heating tubes 31 which are heated to a high temperature and the case 32 has an open top with grids thereon. Stones 33 are put on the grids to absorb the heat from the heating tubes 31 and release far infrared beams. The stones 33 might burn the users and the far infrared is limited because the stones 33 include limited surfaces. Due to the high temperature of the heating tubes 31, the gap between the heating tubes 31 and the insides of the case 32 has to be wide enough so that the case 32 is bulky.
The present invention intends to provide a heating device that has a compact size and the heating boards are so thin that the heat can be efficiently dispensed and do not hurt the users.